I think the Habs are doing the right thing by keeping Subban down in the AHL to let him really develop without the interruption of coming to the NHL, getting high on himself, hitting a slump, and then never recovering. Let him dominate down in the A and really build his confidence, and his game. He's doing really well down there, but there will be bad games, strings of bad games, that he'll need to learn to accept and play through.
I'm definitely excited to see him up in the NHL, but he'll be that much the better player if they do the right thing with his development - a la Tomas Plekanec.